With the development of high-speed network infrastructure and with the development of large capacity recording media, the absolute quantity of video data that can be handed at a time by the user or by user video equipment has markedly increased. With this trend, various functions that are achieved using a plurality of sets of video data and high-performance applications based on such functions have been emerging. As one of such functions, there is a function called picture in picture. “Picture in picture” is a function for displaying two images at the same time by superimposing a small child frame over the screen (parent frame). This function is used for, for example “multi-angle representation” for displaying a video taken from a different angle of view from that of the video for the parent frame or for “commentary display” for displaying additional information in a commentary style as to the video of the parent frame (for example, displaying a director's commentary video or the like for recording untold stories during shooting the video).
This picture-in-picture function is realized for example by a process made up of decoding two sets of video data over two different layers and superimposing these decoded videos, as shown in FIG. 17.
Further, FIG. 18 shows different display styles of a video in the child frame in picture-in-picture functionality; the child frame may be a rectangular video 1801 or may be a video 1802 having an arbitrary shape. The picture-in-picture function and the method of realizing it are described in for example patent document 1 and others. Patent document 1:
Japanese Patent Application Laid-open 2005-123775